<template>
    <!-- 分页 -->
    <div class="pagination">
        <!-- 分页左边部分 -->
        <button v-if="pageNo!==1" @click="$emit('getPageNo',pageNo-1)">上一页</button>
        <button v-if="startNumAndEndNum.start>1" @click="$emit('getPageNo',1)">1</button>
        <button v-if="startNumAndEndNum.start>2">···</button>

        <!-- 分页中间部分，v-for遍历数字 -->
        <button v-for="(page,index) in startNumAndEndNum.end" :key="index" :class="{active:pageNo==page}"
        v-show="startNumAndEndNum.start<=page"   @click="$emit('getPageNo',page)"
            >{{page}}</button>

        <!-- 分页右边部分 -->
        <button v-if="startNumAndEndNum.end<totalPage-1">···</button>
        <button v-if="startNumAndEndNum.end<totalPage" @click="$emit('getPageNo',totalPage)">{{totalPage}}</button>
        <button v-if="pageNo!==totalPage" @click="$emit('getPageNo',pageNo+1)">下一页</button>

        <button  style="margin-left: 30px">共 {{total}} 条</button>
    </div>
</template>
<script>
export default {
    name: "Pagination",
    props: ['pageNo', "pageSize", "total", "continues"],
    computed: {
        //总页数
        totalPage() {
            return Math.ceil(this.total / this.pageSize)         //向上取整
        },
        startNumAndEndNum() {
            let start = 0, end = 0;
            if (this.continues > this.totalPage) { //特殊情况：如果连续页数量比总页数多
                start = 1;
                end = this.totalPage
            } else {
                start = this.pageNo - Math.floor(this.continues / 2)//2
                end = this.pageNo + Math.floor(this.continues / 2)//2
                if (start < 1) {                    //start数字小于1
                    start = 1;
                    end = this.continues;
                } if (end > this.totalPage) {       //end数字大于总页数
                    start = this.totalPage - this.continues + 1
                    end = this.totalPage;
                }
            }
            return { start, end };
        },

    },
    methods:{
        
    }

}
</script>
  
<style lang="less" scoped>
.pagination {
    text-align: center;

    button {
        margin: 0 5px;
        background-color: #f4f4f5;
        color: #606266;
        outline: none;
        border-radius: 2px;
        padding: 0 4px;
        vertical-align: top;
        display: inline-block;
        font-size: 13px;
        min-width: 35.5px;
        height: 28px;
        line-height: 28px;
        cursor: pointer;
        box-sizing: border-box;
        text-align: center;
        border: 0;

        &[disabled] {
            color: #c0c4cc;
            cursor: not-allowed;
        }

        &.active {
            cursor: not-allowed;
            background-color: #409eff;
            color: #fff;
        }
    }
}
</style>
  